Historical Rules · 17 June 2011
Rule 901.9
Official source text from the 17 June 2011 Rules release
When a player leaves the game, all objects owned by that player leave the game. (See rule 800.4a.) If that includes the face-up plane card, the planar controller turns the top card of his or her planar deck face up. This is not a state-based action. It happens as soon as the player leaves the game.